Carrier for recording and method of making the same



March 26, 1940. J. H. -ma BOER ET'AL CARRIE Fon RECORDING AND METHOD or" MAKING THE SAME Filed June 26, 19257 Patented Mar. 26, 1940 UNITED sTATss CARRIER FOR RECORDING AND METHOD F MAKING THE SAME' Jan Hendrik de Boer, Cornelis Johannes Dippei,

and Bermrd -Sybrand Hendrik Stieler, Eindhoven, Netherlands, assignors to N. V. Philips Gloeilampenfabrieken, Eindhoven, Netherlands Application Jnne 26, 1937, Serti No. 150,628

In Germany 12 Claims.

Our invention relates to carriers for mechanically-recorded and optically-reproducible vibration records, and more particularly to covering layers for such carriers.

We shall describe our invention in connection with mechanical recording oi the type described in the U. S. Patent #1,919,116 to James A. Miller; however it is not limited thereto but is applicable to other types of recording in which a carrier having a covering layer is used. In such recording a cutting tool having a V-shaped cutting edge with lan apical angle of about 174 is vibrated perpendicularly to a carrier moved at a constant speed to cut therein an optically-reproducible vibration track whose width variations are a proportional enlargement of its depth variations.

The carriers used for this purpose generally comprise a recording layer of light-transmitting material, a covering layer of opaque material and` having a thickness of about microns or less, and, as a rule, a supporting layer of light-transparent material.

Various types of covering layers have been proposed for this purpose, and very good results are for example obtained by using those of the type described in the U. S. Patent #2,020,861 to van der Willigen, which are made from an opaque or colored colloidal solution, for example, of metals of metal compounds. Such layers give very good results because they are applied in their opaque condition prior to the recording, and thus make further treatment to obtain the coveringcapacity unnecessary and because the granulated structure of the covering layer, which is very important in the recording, is considerably reduced? However, the use of such layers has the disadvantage that they can be produced only in a complicated and involved manner and the manufacture must be very accurately vcarried out. y

In such a method a colored compound is prepared from two or more components in a solution, for example of gelatin, and is then applied to the recording layer, for example by pouring. However, unless special precautions are taken during the manufacture, and particularly during the melting of the gelatin mass, there will be ilocculation of the compound, or an agglomeration or coarsening of the particles, whereby the covering layer will be given a granulated structure which deleteriously affects the optical reproduction. This diiilculty increases with the more times the gelatin mass containing the colored compound has to be melted, and as the mass has to be melted at least three times, i. e., during the production of the compound, during the ill- Juny is, me

(ci. :1t-4a) tration, and during the pouring, the harmful granulation is quite likely to occur. Y

The object of our invention is to overcome the above difficulties and to provide a simple method of forming a covering layer which will meet all conditions as regards bothv the recording and the reproduction. A further object of our invention is to provide a very thin covering layer of uniform thickness.

In accordance with the invention we form the covering layer by the chemical reaction between two or more substances.

More particularly, we provide within the recording layer, or a layer applied thereto, one or more molecularlyor colloidally-dispersed sub- 1f stances, and apply to lthe carrier, either before or after recording, one or more substances which chemically react with the former substances tov form a colored compound in a superficial zone of the recording layer or of the layer applied thereto. Instead of adding the former substances to a recording layer or a layer applied thereto, they may form the material of those layers.

The term colored compound as used herein and in the claims, is to be understood to mean a compound which is substantially impervious to the rays of light used for reproduction, i. e., for photographic copying or optically reproducing. It is not absolutely necessary that, after the chemical reaction, the covering layer be co1- ored in conformity with only a few selected colors of the visible spectrum, but it may be opaque to white light. Furthermore, the covering layer may have no visible color, but absorbs only the infra-red light which may be used for direct reproduction, the ultra-violet light which may be advantageouslyused for copy, or both of these lights. In View of the above, the terms blackcned, opaque, coloured, etc., will be used synonymously to indicate that the compound is 40 opaque to the type of' light to be used in the reproduction.

We prefer to use as the components of the chemical reaction, substances which react -to form an insoluble colored compound, such as an insoluble colored metal sulphide, produced for example by blackening a sulphide-producing metal salt with a sulphide solution. An insoluble compound is particularly advantageous because, due to this insolubility, the component which is added to produce the coloration is prevented from diffusing to an undesired degree, i. e., the insoluble compound forms an impenetrable protective iilm. This eliminates the necessity of aci, time there is no danger'of the covering layer be.

The method of the invention may be carried For example," the .re-V cording layer may be provided with or formed out in various manners.

of a substance which chemically reacts with one or more substances which are later added to forni an opaque compound which, by properly selecting the substances, extends to a depth of about 10p..

a covering layer is applied by rolling orv pouring, the above method has the advantage that only ther recording layer, which is preferably provided on a supporting Iayenneed be produced mechanically. This simplifies the manufacture of the carriers in mass production, while at the same coming loosened fromthe recording layer. Furthermore, if the covering layer of the invention becomes damaged for -some reason, it' may be readily restored, for example by applying to the defective spot some of the added component which reacts with the component remaining below the originally-formed covering layer.

In another embodiment we provide the ilrst component in a separate layer which isapplied to the recording layer, whereby the colored compound cannot be formed to a depth greater than the thickness of the former layer, and a welldened boundary between the covering and recording layers is obtained, regardless of the type of components used and without employing special precautions during the manufacture.

In the above embodiments the color-forming reaction may take place before or after the recording, but color formation before recording has the advantage that reproduction may be eiected immediately after the recording and without subsequent treatment of the carrier. On the other hand, application of the added component after recording has the advantage that the particles cut from the carrier are uncolored and thus if not completely removed will not cause distortion in the reproduction.

We prefer to 'add the added component dissolved in a 'volatile solvent, particularly'when the first component is provided in a separate layer, as in this case there is no possibility of the solvent affecting the depth of the colored compound.

By adding both components after the recording, we insure that the advantageous cutting properties of the recording layer will not be deleteriously affected thereby. In such cases we prefer to apply both components dissolved in volatile solvents, because this permits I prompt reproduction.

Instead of adding the added-component as a liquid it may also be applied as a gas or vapor.

Further. advantages of our invention will apn pear as the description progresses.

In order that the invention may be clearly understood and readily carried into eifect, we shall describe same in more detail with reference to the accompanying drawing, in which:

Figure 1 is an enlarged sectional view of a carrier in which a soundtrack is being recorded;

Figs. 2, v3 and 4 are-enlarged sectional views of carriers according to the invention; and

Thus in contradistinction to the method lof l the above-mentioned Patent #2,020,861, in which arancia Fig. 5 is a perspective View of a carrier in which la sound track is being recorded and illustrated the method of the present invention.

Referring to Figure 1, a cutting tool l having a V-s'haped cutting edge forming an apical angle a of about 174, is vibrated in the direction of the double-headed arrow and in accordance with `the vibrations being recorded, to cut an optically-reproducible vibration track into a carrier I5, which is moved at a constant speed perpendicularly to the plane of the drawing. Carrier I I5 comprises' a supporting layer 5 of transparentA material, such as Celluloid, e. recording layer 4 of transparent material of `good cutting properties, for instance gelatin or regenerated cellulose and having a thicknes of about 65a, and an 'opaque covering layer 3 having a thickness less than 10a. During recording, portions of layer 3, as well as of layer 4, are removed-whereby a vibration track having width variations of about 40 times the depth variations is produced. As has been stated, the covering layer 3, in accordance with yprior-art methods, was applied mechanically in a blackened condition, for example by applying, for instance byrollers or by pouring, a colored mass upon the' recording layer 4.

In Figure 2, which illustrates one embodiment I of the invention, a recording layer 6 of gelatin or the like is used, and is provided during the..`

manufacture with one or more substances which are homogeneously distributed throughout'the entire layer, i. e. are colloidally or molecularly dispersed therein, and which are subsequently blackened to form a covering layer 8 by the application of a second coloring compound. In contradistinction to the prior-art carrier shown in Fig. 1, it will be noted `that in accordance with the invention, only the black layer 8 is formed at the surface of the recording layer 6 and no covering layer as such is applied. As has been stated, the second color-forming component may be added either before or after the recording; however if this substance is added before the recording, reproduction may be eilected immediately after recording. Instead of adding one of the color-forming components before the recording, both of these components may be added after the manufacture of the carrier, with the result that the rst component will penetrate only superficially into the recording layer, and when thev second component is applied, only a very thin covering layer will be produced. To obtain a still thinner covering layer we prefer to use components which chemically react to produce an insoluble compound, which, as has been stated, restricts the diffusion of the added color-forming component.

The carrier shown in Figure 3 comprises a supporting layer 5 of Celluloid, a recording layer Il of gelatin, and a third layer I6 consisting, for example, of gelatin and to which, in accordance with the invention, a color-forming component has been added so as to be homogeneously distributed throughout, as indicated by the dotted right-hand portion. The second color-forming component is then applied, either before or after recording, whereby a coloring compound is formed, as indicated by the sectioned left-hand portion of layer I6. It will be noted that in this embodiment the formation of the colored compound is restricted to layer I6, and thus it is unnecessary to use components which produce an insoluble colored compound or to take special precautions during application of the second component. On the other hand, it is not absolutely necessary that layer VIl be colored throughout, but similarly to the embodiment shown in Fig. 2, only a superficial zone of this layer may be colored by allowing the added component to act for only a short time. Instead of which comprises a recording layer I8 of transparent material 'of good cutting properties, such as gelatin, provided with a plurality of corrugations I9. A covering layer is formed thereon by the method of the present invention. In this case a cutting tool having a straight cutting edge parallel to the axis oi' the carrier, and is vibrated perpendicularly to the surface of the carrier to produce a plurality of additively-reproducible vibration tracks. The recording layer I8 may be made considerable thinner than that shown in Fig. 1, for instance smaller than 10a, whereas the covering layer 20, for practical reasons may also be thinner, for example 2a.

The method of the present invention will be explained in more detail with reference to the following examples:

Example I A carrier is formed with a recording vlayer of gelatin, to which lead acetate in a suitable concentration, has been added in homogeneous distribution during the production of the gelatin mass, for example 19 or 20 grams of lead acetate for every 100 grams of air-dry gelatin. The gelatin layer so formed is then treated with an ammonium sulphide developer for example in a concentration of 1N, in an aqueous solution, to form lead sulphide, which causes a blackening of the surface of the layer.

Example II ever this diiiiculty does not arise in the method of f Example II because the lead acetate is not provided throughout the gelatin layer, but only to a comparatively slight depth.

Example III A carrier such as shown in Figure 3 and having a separate covering layer I6, for instance of gelatin, is treated in the manner set forth in Examples I and II. In this case, however, the color formation under all conditions is restricted to layer I6.

Example 1V The methods of Examples I, II, and III may be advantageously modiiied in such a manner that the formation of the colored compound does not take place until after the mechanical recording. This can be eifected in the manner set forth in Examples IVa and IVb:

Example IVa During the manufacture of the carrier, the recording layer is provided throughout its entire thickness with the lead acetate solution. Subsequently the mechanical recording is effected, for example 'in the manner described in connection with Figure 1. The parts of the covering layer which remain, i. e. the portions thereof which bound the track and are higher than the track. are then colored by applying thereto the second component, for example by means of a cylindrical roller.

' Example IVb The method set forth in Example IVa may be eifected by applying the first component to the surface of the recording layer, in accordance with Example II. In this case the recording may take place through the still uncolored but yet substantially present covering layer. 'I'he method as set forth in Example III may also be used. Afterthe recording, the remaining portions of the covering layer are colored by applying the added coloring component in a simple manner, for example by means of a pad, whereby the track remains transparent.

Example V A method of carrying the invention into effect will be explained in connection with Fig. 5, in which a carrier comprising a supporting layer 5 of Celluloid and a recording layer 6 of gelatin, is moved in the direction of the arrow beneath a cutting tool I. Disposed before the tool I is a pad III which applies to the carrier a solution of leadacetate whereby, as set forth in Example II, a thin layer II of lead acetate, indicated by crosshatching, is produced at the surface of the gelatin layer 6. A vibration track I2 is then produced in the manner described ln connection with Figure 1, whereby portions of the recording layer and the lead acetate are removed. After the re cording, the carrier passes beneath a second pad I4, which applies to the surface of layer 6, an ammonium sulphide developer which chemically reacts with the lead acetate to produce an opaque covering layer 9.

Instead of using lead acetate, as mentioned in Examples I to V inclusive, good results are obtained by using other suitable lead salts and sulphide-producing metal salts, for example copper salts, mercurous salts, nickel salts, etc. Furthermore, instead of using ammonium or alkaline sulphide solutions, a gas current of hydrogen sulphide may be applied to the layer containing the sulphide-producing metal salts, whereby similar colored compounds are obtained. The method described in Example IVa, however, cannot be carried out with the use of a gas because portions of the track would be colored.

Example VI The methods described in Examples I to V may be carried out with other chemical reactions, for example mercurous nitrate may be used as the substance provided in the recording layer, and an ammonia-solution may be used as the added component whereby the black precipitate NHzHgzNO; is produced. Instead of using an ammonia solution, a wet NH3 gas may be used; however this cannot be done by the method of Example IVa.

Example VII If, in Examples I to IV, potassium ferrocyanide is used as the first component, the desired coloration can be obtained by applying a ferrie salt solution, which acts on the potassium ferrocyanide to produce a colloidally-dispersed darkblue Prussian blue.

Example VIII Following the method given in Examples I to V, indigo may be provided in the recording layer; however, as this substance is insoluble it must be provided in a different manner. This may be effected by reducing the indigo, for example by means of rongalite (sodium sulpho-oxilate), or a hyposulphide salt, for instance Na2S2O4, in which case the indigo is dissolved as indigo white, which is provided in the recording layer. The carrier is then treated with an oxidizing solution whereby the indigo white is transformed into the blue insoluble colloidally-dispersed indigo which forms thecolored compound. Instead of using an oxidizing solution, the coloration may be obtained by treatment with gas, or by exposing the carrier to atmospheric air. The use of an oxidizing agent in the form of a gas or vapor cannot` however, be used in the method described in Example IVa.

Example IX It is also possible to obtain the coloration necessary for opticalreproduction by coloring the material of the recording layer itself after the recording by adding suitable substances thereto. For example, a recording layer consisting of gelatin or or similar decomposed a1- buminous substances, may be treated with an alkaline copper sulphate solution, which results in the present instance in a bluishl to reddishviolet colored compound.

On the other hand, the amino-acid present in the gelatin layer is capable of coupling with a diazo-benzene-sulphonic solution, and a colcred compound may be obtained by treatment with this solution and then painting the carrier with a 2N solution of soda.

From the above examples it will be seen that the colored compound is produced in a simple manner at the desired place and in a non-liquid milieu, and afterbeing formed never has to be melted again, and therefore the danger of granulation is practically avoided. Furthermore, the compound remains homogeneously distributed at the point at which it is produced because the rst component, vis already provided in a molecular or colloidal dispersion in the protective milieu and remain in this state of dispersion. In addition, the chemical action itself brings about a well-defined boundary between the colored and uncolored portions of the carrier, because the second component, when being added, is transformed during the color-forming process by chemical reaction and is consumed, with the result that the formation of an unsharp boundary as would be produced for example if a solution of coloring material were diffused into a gelatin layer, is avoided.

While we have described our invention in connection with specific examples and specific applications, we do not wish to`be limited thereto, but desire the appended claims to be construed as broadly as permissible in view of the prior art.

What we claim is:

1. A method of producing an opaque lcovering lay'er in a carrier for mechanically-recorded and optically-reproducible vibration records and having a recording layer of transparent material, the steps of forming upon the surface of said recording layer a thin layer containing a colorforming @substance colloidallyor molecularlydispersed, applying a second colorformlngsub stance to the surface of said thin layer, and forniing a colored compound by the chemical reaction between said substances. A

2. A method of producing an opaque covering layer in a carrier for mechanically-recorded and optically-reproducible vibration tracks and having a recording layer of light-transparent material, the steps of applying to the surface of said layer a color-formingl substance to form a layer of said substance colloidallyor molecularly-` dispersed in a superficial zone of the recording layer, applying to the surface of the recording layer a second color-forming substance dissolved in a volatile solvent, and forming a colored compound Within said superficial zone by the chemical reaction between said substances.

3. A method of producing an opaque covering layer in a carrier for mechanically-recorded and optically-reproducible vibration records, the steps of providing within ay superficial zone of the carrier a layer of a color-forming substance colloidallyor molecularly-dispersed, applying a second color-forming substance in a gaseous form to the surface of the carrier, and forming within said superficial zone a colored compound by the chemical reaction between said substances.

4. A method of producing an opaque covering layer in a carrier adapted to receive a mechanically-recorded and optically-reproducible vibration record and provided with a color-forming light-transparent material provided with a color-forming substance colloidallyor molecularlydispersed therein, comprising the steps of applying a second color-forming substance to the surface of the recording layer, and forming a colored compound in a superficial zone of the recording layer by chemical reaction between said substances.

6. A method of producing an opaque covering layer in a carrier adapted to receive a mechanically-recorded and optically-reproducible vibration record and` having a recording layer of light-transparent material provided with a co1- or-forming substance colloidallyor molecularlydispersed in a surface portion thereof. comprlsing the steps of applying a second color-forming substance to the surface of the recording layer, and forming a colored compound in a superficial zone of the carrier by chemical reaction between said substances.

7. A method of producing an opaque covering layer in a carrier adapted to receive a mechanically-recorded and optically-reproducible vibration record and provided with a color-forming substance colloidallyor molecularly-dispersed in a surface portion thereof, comprising the steps of applying a second color-forming substance to the surface of the carrier, and forming an insoluble colored compound in a superficial zone of the carrier by chemical reaction between said substances.

8. A-method of producing an opaque covering layer in a carrier adapted to receive a mechan ically-recorded and optically-reproducible vibration record and provided with a color-forming substance colloidallyor molecularly-dispersed in a surface portion thereof, comprising the steps of applying a second color-forming substance to the surface of the recording layer, and forming a colored insoluble metal sulphide in a supercial zone of the carrier by chemical reaction between said substances.

9. A method of producing an opaque covering layer in a carrier adapted to receive a mechanically-recorded and optically-reproducible vibration record and provided with a metal salt co1- loidallyor molecularly-dispersed in a surface portion thereof, comprising the steps of applying a sulphide solution to the surface of the carrier, and forming a colored insoluble sulphide in a superficial zone of the carrier by chemical reaction between said solution and said metal salt.

10. A method of producing an opaque covering layer in a carrier adapted to receive a mechanically-recorded and optically-reproducible vibrationrecord and provided with a color-forming substance colloidallyor molecularly-dispersed in a surface portion thereof, comprising the steps of applying to the surface of the carrier a second color-forming substance dissolved in a volatile prising a recording layer of light-transparent material having a thin supercial portion acting as a covering layer and containing a colored compound formed in situ by a chemical reaction between color-forming substances and molecularlydispersed in said supercial zone, a portion of said recording layer beneath said covering layer containing one of said color-forming substances.

JAN HENDRIK DE BOER. CORNELIS JOHANNES DIPPEL, BERNARD SYBRAND HENDRIK STIELER. 

